So, the past few days, I've noticed these small caterpillar like insects on my grape plant leaves. The insect is always on the underside of the leaf on one of the veins. It's very small, about a half an inch long, and a pale green color. The caterpillar insect also has a black/brown stem thing coming out of the head? Also, around the same time as these insects showing up, there have been shiny trails on the topside of the leaf near the veins. Can you tell me about this insect if you know what it is? I think it may be feeding on the plant...